Django自定义字段方法不在mysql中创建枚举字段

我的代码如下所示：

class CharMaxlength25Field(models.Field):
    def db_type(self, connection):
        return 'enum(android,ios)'



class search(models.Model):

    class Meta:
        db_table = 'search'

    city_name = CharMaxlength25Field()

通过这段代码，我试图在mysql中创建枚举字段。现在，当我尝试使用python manage.py makemigrations步骤运行此模式时，出现以下错误：

django.db.utils.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'android,ios) NULL' at line 1")

尝试添加引号：

class CharMaxlength25Field(models.Field):
    def db_type(self, connection):
        return 'enum("android","ios")'